Endometriosis is a poorly understood gynecologic condition defined as the presence of endometrial tissue at ectopic sites. This condition is characterized by severe pelvic pain, dyspareunia, dysmenorrhea, and infertility. Endometriosis continues to incapacitate and affect the well being, productivity, and lifestyle of millions of women, whilst imposing a challenge to medical doctors and researchers alike. The cause of endometriosis remains elusive, although environmental, immunological and genetic factors have been implicated. The limited treatments available are not curative, and definitive diagnosis requires surgery, since there are no specific diagnostic tests for this disease. We have been studying the molecular and genetic aspects of endometriosis in Puerto Rico, with the purpose of filling an important gap in the knowledge of this disease in general, and also as its applies to the Hispanic population in particular. Preliminary studies in our laboratory have shown that previously reported genetic associations to endometriosis do not hold true in our population. These findings highlight the importance of carrying out association studies in different populations, since genetic variations and their involvement in disease susceptibility are likely to vary across ethnic backgrounds. Also, we have observed that genetic associations differ in patients with and without a family of endometriosis. Finally, we have used DNA microarrays, subtractive hybridization and genetic linkage analysis to identify candidate genes/genomic regions which potentially represent susceptibility loci for endometriosis. We hypothesize that genetic variations in candidate genes are associated with susceptibility to endometriosis. Also, we hypothesize that genetic associations differ in patients with familial versus sporadic endometriosis. The main goal of the present proposal, therefore, is to elucidate the mechanisms involved in the genetic susceptibility to endometriosis in a Puerto Rican population, and to determine if those mechanisms vary according to family history status. Identification of such variations is of critical importance to better understand the etiology of endometriosis, to design specific non-invasive diagnostic tests and, ultimately, to develop a cure for this incapacitating condition. Due to important links between endometriosis and infertility, pregnancy loss and ectopic pregnancy, the information uncovered by these studies will greatly impact the field of reproductive science, a target issue addressed in the Healthy People 2010 report (9-12).